I use Grocery Gadget. So far I've used it mostly for inventory purposes. I wanted to be able to have a list of everything in the pantry and freezers with me when I get to the store. I like to stock up when something is at its lowest price. If I see an unadvertised special, by using this app I'll know whether I have any at all or how many I have at home. I don't have everything inventoried yet, but I'm getting there. The app allows me to input all the information I could possibly want to input. I can scan UPCs and have the item pop into my list, and I can categorize items.
I like Grocery Gadget because there is both a smartphone app and a web-based application that I can access on my computer. Also, I had a long list of items on my Palm, and I was able to import that list into this app. The same list will sync with other family members' smartphones.
Other people have entered items into the Grocery Gadget database. Occasionally when I scan a food item, I will find that someone else entered the wrong name for that UPC, or the way they entered the food name is not the way I would prefer. It takes a little work to get everything just right, but when I'm done I'll feel much more in control of my shopping and my stockpiles.